2013年3月9日土曜日

タモキシフェン:5年でやめるか、10年続けるか? ATLAS試験の結果

今の日本のEBMではタモキシフェンを5年以上続ける必要性はないというのが、乳癌診療ガイドライン(2011)のコンセンサスである。臨床研究の中には5年以上続けた方が良いという論文もある。差がないとの報告もある。ガイドラインでは差がないとの統一見解で対処している。

今回ここに掲示するのは、ATLASの報告である。早期乳癌でER陽性の人にまず5年間タモキシフェンをのませた。5年終了後に2群にわけて、一群には更に続けて5年間(計10年)のんで貰った。そんな人が3400人ずついると思いねぇ。かれらはどうなったかというと・・・・・
1)reduced breast cancer mortality (331 deaths vs 397 deaths, p=0·01),
2)reduced overall mortality            (639 deaths vs 722 deaths, p=0·01)

今回の結果では10年のませた方がよいという結果である。さて今後はどうするかしらんね。

The Lancet, Volume 381, Issue 9869, Pages 805 - 816, 9 March 2013
Published Online: 05 December 2012

Long-term effects of continuing adjuvant tamoxifen to 10 years versus stopping at 5 years after diagnosis of oestrogen receptor-positive breast cancer: ATLAS, a randomised trial 


 the Adjuvant Tamoxifen: Longer Against Shorter (ATLAS) Collaborative Group

Summary

Background

For women with oestrogen receptor (ER)-positive early breast cancer, treatment with tamoxifen for 5 years substantially reduces the breast cancer mortality rate throughout the first 15 years after diagnosis. We aimed to assess the further effects of continuing tamoxifen to 10 years instead of stopping at 5 years.

Methods

In the worldwide Adjuvant Tamoxifen: Longer Against Shorter (ATLAS) trial, 12 894 women with early breast cancer who had completed 5 years of treatment with tamoxifen were randomly allocated to continue tamoxifen to 10 years or stop at 5 years (open control). Allocation (1:1) was by central computer, using minimisation. After entry (between 1996 and 2005), yearly follow-up forms recorded any recurrence, second cancer, hospital admission, or death. We report effects on breast cancer outcomes among the 6846 women with ER-positive disease, and side-effects among all women (with positive, negative, or unknown ER status). Long-term follow-up still continues. This study is registered, number ISRCTN19652633.

Findings

Among women with ER-positive disease, allocation to continue tamoxifen reduced the risk of breast cancer recurrence (617 recurrences in 3428 women allocated to continue vs 711 in 3418 controls, p=0·002), reduced breast cancer mortality (331 deaths vs 397 deaths, p=0·01), and reduced overall mortality (639 deaths vs 722 deaths, p=0·01). The reductions in adverse breast cancer outcomes appeared to be less extreme before than after year 10 (recurrence rate ratio [RR] 0·90 [95% CI 0·79—1·02] during years 5—9 and 0·75 [0·62—0·90] in later years; breast cancer mortality RR 0·97 [0·79—1·18] during years 5—9 and 0·71 [0·58—0·88] in later years). The cumulative risk of recurrence during years 5—14 was 21·4% for women allocated to continue versus 25·1% for controls; breast cancer mortality during years 5—14 was 12·2% for women allocated to continue versus 15·0% for controls (absolute mortality reduction 2·8%). Treatment allocation seemed to have no effect on breast cancer outcome among 1248 women with ER-negative disease, and an intermediate effect among 4800 women with unknown ER status. Among all 12 894 women, mortality without recurrence from causes other than breast cancer was little affected (691 deaths without recurrence in 6454 women allocated to continue versus 679 deaths in 6440 controls; RR 0·99 [0·89—1·10]; p=0·84). For the incidence (hospitalisation or death) rates of specific diseases, RRs were as follows: pulmonary embolus 1·87 (95% CI 1·13—3·07, p=0·01 [including 0·2% mortality in both treatment groups]), stroke 1·06 (0·83—1·36), ischaemic heart disease 0·76 (0·60—0·95, p=0·02), and endometrial cancer 1·74 (1·30—2·34, p=0·0002). The cumulative risk of endometrial cancer during years 5—14 was 3·1% (mortality 0·4%) for women allocated to continue versus 1·6% (mortality 0·2%) for controls (absolute mortality increase 0·2%).

Interpretation

For women with ER-positive disease, continuing tamoxifen to 10 years rather than stopping at 5 years produces a further reduction in recurrence and mortality, particularly after year 10. These results, taken together with results from previous trials of 5 years of tamoxifen treatment versus none, suggest that 10 years of tamoxifen treatment can approximately halve breast cancer mortality during the second decade after diagnosis.

Funding

Cancer Research UK, UK Medical Research Council, AstraZeneca UK, US Army, EU-Biomed.

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